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Technical  Paper  1 


DEPARTMENT  OF  THE  INTERIOR 

FRANKLIN  K.  LANE,  SECRETARY 
BUREAU  OF  MINES 

VAN.  H.  MANNING,  DIRECTOR 


THE  SAMPLING  OF  COAL  IN 
THE  MINE 


BY 


JOSEPH  A.  HOLMES 


WASHINGTON 

GOVERNMENT  PRINTING  OFFICE 
1918 


The  Bureau  of  Mines,  in  carrying  out  one  of  the  provisions  of  its  organic  act — to 
disseminate  information  concerning  investigations  made — prints  a  limited  free  edi- 
tion of  each  of  its  publications. 

When  this  edition  is  exhausted,  copies  may  be  obtained  at  cost  price  only  through 
the  Superintendent  of  Documents,  Government  Printing  Office,  Washington,  D.  C. 

The  Superintendent  of  Documents  is  not  an  official  of  the  Bureau  of  Mines.  His  is 
an  entirely  separate  office  and  he  should  be  addressed: 

SUPERINTENDENT  OF  DOCUMENTS, 

Government  Printing  Office, 

Washington,  D.  C. 

The  general  law  under  which  publications  are  distributed  prohibits  the  giving  of 
more  than  one  copy  of  a  publication  to  one  person.    The  price  of  this  publication  is 
5  cents. 
2 


Revised  edition.     July,  1918. 
First  edition  issued,  May,  1911. 


CONTENTS. 

Page. 

General  statement 5 

Need  of  care  in  sampling 5 

Relation  of  mine  samples  to  commercial  samples 6 

Collecting  outfit  or  sampling  kit 7 

Carrying  bag 8 

Sampling  cloth 8 

Portable  mortar 8 

Pestle 9 

Spring  balance ^ 9 

Screen 9 

Sampling  scoop , 9 

Brush 9 

Measuring  tape 9 

Sample  can 9 

Adhesive  tape 9 

Pick  and  shovel . 10 

Preliminary  details 10 

Selecting  places  for  sampling. . . , 10 

Number  of  samples  to  be  collected 11 

Method  of  sampling 11 

Cleaning  off  the  face  of  the  coal 11 

What  to  include  in  the  sample 11 

Collecting  and  preparing  the  sample 12 

The  can  should  be  completely  filled 13 

Labeling 13 

Sealing  the  can 13 

Notes 13 

Prompt  forwarding  and  analysis  of  samples 14 

Sending  notification  cards 14 

Blank  forms  for  collectors 14 

Publications  on  the  sampling  and  analysisof  coal 21 


ILLUSTKATIONS. 

FIGURE  1.  Sampling  outfit 


3 


382215 


THE  SAMPLING  OF  COAL  IN  THE  MINE. 
By  JOSEPH  A.  HOLMES. 


GENERAL  STATEMENT. 

Systematic  collection  and  analysis  of  coal  samples  in  connection 
with  investigations  relating  to  fuels  belonging  to  or  for  the  use  of 
the  United  States  Government  and  to  the  character  and  value  of  the 
fuel  in  the  public  lands  were  begun  by  the  Government  in  1904. 
The  method  of  collecting  mine  samples,  with  the  various  modifica- 
tions and  improvements  found  desirable  through  experience,  has  been 
continued  from  that  time  and  is  the  method  followed  by  those  geolo- 
gists of  the  United  States  Geological  Survey  who  have  been  examin- 
ing the  coal  deposits  on  or  near  the  public  lands  and  by  those  mem- 
bers of  the  Survey  arid  the  Bureau  of  Mines  who  have  continued  the 
work  of  analyzing  and  testing  the  coal  from  the  various  fields  in 
the  United  States. 

The  following  statement  of  the  system  of  mine  sampling  in  use 
by  the  Geological  Survey  and  the  Bureau  of  Mines  has  been  revised 
by  Messrs.  M.  R.  Campbell,  George  H.  Ashley,  and  David  White,  of 
the  Geological  Survey,  and  Messrs.  G.  S.  Rice  and  G.  S.  Pope,  of  the 
Bureau  of  Mines. 

NEED  OF  CARE  IN  SAMPLING. 

In  dealing  with  coals  no  less  than  in  dealing  with  ores  the  taking 
of  samples  requires  fully  as  much  care  as  does  the  making  of  the  analy- 
sis or  assay,  for  if  the  sampling  is  not  properly  done  and  the  sample 
does  not  fairly  represent  the  coal,  then  the  analysis,  however  care- 
fully and  accurately  made,  is  misleading.  It  may  be  impossible  or 
impracticable  to  obtain  another  sample  from  the  mine,  whereas  if 
an  analysis  is  wrong,  another  analysis  can  easily  be  made  of  the  origi- 
nal sample,  as  the  sample  sent  to  the  laboratory  is  many  tunes  the 
quantity  required  for  the  actual  laboratory  test. 

In  the  field  work  of  the  Bureau  of  Mines,  samples  are  frequently 
required  of  special  shipments  of  coal  as  it  is  loaded  into  railroad  cars 
at  the  mine  or  as  it  is  unloaded  from  railroad  cars  into  bins  or  ships. 
Printed  instructions  regarding  methods  of  sampling  such  shipments 
are  given  in  Technical  Paper  133,  entitled  "  Directions  for  Sampling 
Coal  for  Shipment  or  Delivery."  The  underlying  principles,  as  well 
as  the  details  of  methods  given  in  Technical  Paper  133,  are  printed  in 
Bulletin  116,  "Methods  of  Sampling  Delivered  Coal";  that  bulletin 

5 


6  THE   SAMPLING   OF    COAL   IN    THE    MINE. 

also  treats  of  the  factors  that  influence  the  accuracy  of  sampling; 
considers  the  different  constituents  of  coal  in  their  effects  on  its  value; 
refers  to  the  results  of  experimental  sampling;  describes  and  illus- 
trates the  mechanical  preparation  of  samples;  describes  the  specifica- 
tion method  for  the  purchase  of  coal  and  gives  types  of  Government 
coal  specifications;  and  gives  specifications  and  details  for  the  con- 
struction of  sample  containers,  riffles,  etc. 

The  purpose  of  this  paper  is  to  describe  briefly  the  method  now  fol- 
lowed by  the  Bureau  of  Mines  and  the  United  States  Geological  Survey 
in  an  endeavor  to  take  mine  samples  that  fairly  represent  the  beds  of 
coal  that  are  examined  and  that  show,  for  the  places  sampled,  the 
commercial  possibilities  of  these  beds.  It  is  of  the  utmost  importance 
that  the  sampling  be  done  in  a  systematic  manner,  according  to  a 
prearranged  plan,  and  that  the  same  procedure  always  be  followed 
where  circumstances  permit.  Wherever  it  is  possible,  unless  special 
samples  are  desired  for  a  particular  purpose,  only  clean,  fresh  coal 
should  be  sampled,  and  all  dried,  weathered,  or  long-exposed  coal 
should  be  avoided.  When  weathered  coal,  either  in  the  outcrop  or  in 
pillars,  or  other  special  samples  are  collected,  the  particular  character- 
istics of  each  sample  should  be  clearly  described. 

RELATION  OF  MINE  SAMPLES  TO  COMMERCIAL  SHIPMENTS. 

Experience  obtained  by  the  Bureau  of  Mines  during  recent  years 
has  plainly  shown  the  importance  of  mine  sampling  in  determining 
the  character  of  the  coal  that  may  be  produced  by  any  given  mine  or 
district;  for  example,  thousands  of  mine  samples  have  been  taken  for 
the  Navy  in  determining  what  mines  have  coal  suitable  for  naval 
uses.  Consistent  systematic  sampling  has  shown  the  value  of  such 
procedure.  But,  on  the  other  hand,  the  experience  thus  gained  has 
fully  shown  that  mine  samples  generally  may  not  represent  com- 
mercial coal,  as  regards  the  ash  content  and  heating  value,  and  that 
great  caution  must  be  exercised  in  estimating,  from  the  basis  of 
mine  samples,  the  grade  of  coal  shipped,  for  frequently  the  ash  of  the 
commercial  coal  may  be  several  per  cent  higher  than  the  ash 
found  in  the  mine  samples,  and  the  moisture  in  high-moisture  coals 
"as  received"  may  be  several  per  cent  lower.  The  reasons  for  this 
difference  are  as  follows : 

1 .  Care,  or  lack  of  care,  by  miners — who  may  be  naturally  careful, 
indifferent,  or  careless — in  cleaning  from  the  coal  sent  to  the  tipple  the 
bone,  "sulphur,"  or  "slate"  included  in  the  coal  bed.  The  mixing  in 
of  pieces  of  the  roof  and  floor  is  often  the  principal  source  of  much  of 
the  impurities  in  the  coal  shipped,  and  this  is  particularly  true  where 
the  roof  is  shaly  or  there  is  a  "  draw-slate, "  or  the  under  clay  is  so 
soft  that  it  gets  picked  up  in  shoveling  loose  coal  from  the  floor  of 
the  working  place. 


COLLECTING   OUTFIT   OR   SAMPLING    KIT.  7 

2.  Degree  of  discipline  and  supervision  exercised  by  underground 
bosses  over  the  miners  loading  coal. 

3.  Character  of  mechanical  cleaning  apparatus  at  the  tipple  and 
washery. 

4.  Whether  there  are  enough  pickers  or  trimmers,  or  washery  men, 
and  whether  these  men  are  careful  or  careless  in  their  methods. 

5.  Whether  the  coal  separates  readily  from  the  roof  and  shale 
partings,  or  whether  it  is  " frozen"  to  them  and  can  not  be  separated 
without  loosing  much  of  the  coal. 

In  other  words,  the  natural  condition  of  the  coal,  the  labor,  the 
mechanical  arrangements,  and  the  supervision  may  cause  so  great  a 
variation  from  the  results  indicated  by  the  mine  sampling,  that  to 
consider  the  mine  samples  as  representing  commercial  shipments 
might  be  misleading.  This  is  particularly  true  of  coal  from  dirty 
coal  beds  containing  many  partings,  or  coal  beds  with  a  friable  roof 
or  a  soft  bottom. 

The  mine  sample  represents  the  quality  that  can  be  obtained  when 
the  impurities  can  be  readily  separated  from  the  coal,  practically 
perfect  mechanical  appliances  are  used,  and  extreme  care  is  taken 
by  the  men  in  the  mine  and  at  the  tipple. 

Mine  samples  and  delivery  samples  both  must  continue  to  be  taken, 
one  as  a  check  on  the  other.  If  coal  of  a  particular  character  is 
needed,  and  the  mine  samples  do  not  disclose  that  the  coal  is  suitable, 
it  is  idle  to  expect  that  the  commercial  coal  will  be  satisfactory. 
Hence,  for  large  users  of  coal  the  mine  sampling  should  be  done 
first  and  the  sampling  of  delivered  coal  should  follow.  The  mine 
operators  themselves  can  benefit  by  following  the  two  kinds  of 
sampling  in  order  to  insure  that  their  product  is  being  so  cleaned  as 
to  give  the  best  results  possible.  If  the  difference  between  the  mine 
samples  and  the  samples  from  shipments  is  too  great  there  is  evi- 
dently need  of  changing  the  method  or  the  appliances.  Dirty  coal 
not  only  means  a  loss  of  heat  and  increase  of  labor  to  the  consumer, 
but  also  a  great  loss  to  the  country  through  the  transportation  of 
worthless  refuse  and  this  loss  increases  with  the  distance  the  coal 
has  to  be  hauled. 

Mine  sampling,  therefore,  is  invaluable  in  studying  the  possibilities 
of  improving  the  quality  of  coal  shipments,  and  of  determining  the 
advisability  of  installing  any  cleaning  or  washing  machinery  and 
the  type  of  cleaning  machinery  best  adapted  to  the  character  of  the 

coal  and  the  impurity  to  be  separated. 

. 

COLLECTING  OUTFIT  OB  SAMPLING  KIT. 

The  coal-mine  sampling  outfit  (fig.  1)  used  by  the  Bureau  of  Mines 
comprises  the  following  articles :  Carrying  bag,  sampling  cloth  (heavy 
oilcloth) ,  portable  mortar  and  pestle,  spring  balance,  screen,  sampling 


8 


THE   SAMPLING   OF   COAL   IN   THE   MINE. 


scoop,  chalk,  brush,  measuring  tape,  sample  cans,   adhesive  tape, 

pick,  and  shovel. 

Carrying  lag. — 
The  bag  used  for  car- 
rying the  sampling 
outfit  and  the  col- 
lected samples  is  of 
leather,  has  a  shoul- 
der strap,  and  meas- 
ures 13  by  12  by  3 
inches. 

Sampling  cloth. — 
For  collecting  the 
cuttings  chipped 
from  the  face  of  the 
coal  a  stout  sheet  or 
blanket  of  water- 
proof material  is 
used.  The  heavy 
enamel  cloth  known 
as  buggy  cloth  gives 
good  service.  The 
cloth  should  meas- 
ure not  less  than  6 
by  7  feet.  The  en- 
ameled side  of  this 
cloth  should  be  laid 
next  to  the  ground 
to  keep  out  moisture 
and  to  prevent  frag- 
ments of  the  enamel 
from  getting  into  the 
coal  sample. 

Portable  mortar. — 
A  piece  of  J-inch 
board,  10  inches 
square,  covered  on 
the  upper  side  with 
heavy  galvanized 
sheet  iron,  forms  the 
bottom  of  the  port- 
able mortar.  The 
collapsible  sides  are 
of  stout  duck,  and 

are    fastened    at    the    top    to    a    strap-iron    band    that    is    held 


COLLECTING   OUTFIT   OR   SAMPLING    KIT.  9 

up  by  collapsible  strap-iron  posts  fastened  with  set  screws.  The  sides 
are  5  inches  high,  making  the  contents  of  the  mortar  about  500  cubic 
inches. 

Pestle. — The  pestle  for  crushing  samples  consists  of  a  steel  head, 
1  inch  thick  and  3  to  4  inches  square,  with  a  screw  socket  to  receive  a 
wood  handle  about  14  inches  long. 

Spring  balance. — A  good  spring  balance  of  50-pound  capacity, 
graduated  preferably  to  one-half  pound,  is  used  for  weighing  the 
samples. 

Screen. — The  screen  is  of  galvanized-iron  wire  and  has  a  J-inch,  or 
preferably  f-inch,  mesh.  It  is  about  10  inches  square  and  has  a  wood 
frame. 

Sampling  scoop. — The  scoop  recommended  is  made  of  heavy  gal- 
vanized sheet  iron,  with  flat  bottom  and  vertical  sides,  and  is  8  inches 
long,  2  inches  deep,  and  1J  inches  wide.  If  such  a  scoop  is  not  avail- 
able, a  bricklayer's  trowel  or  even  a  wooden  shingle  will  answer  the 
purpose. 

Brush. — A  stiff  brush  or  whisk  broom  is  useful  for  brushing  off 
loose  pieces  of  coal,  stone,  or  dirt  from  the  face  or  roof  at  the  place 
where  the  sample  is  to  be  taken  and  for  removing  the  rejected  quar- 
terings  of  coal  from  the  sampling  blanket.  If  such  a  brush  is  not 
available,  a  piece  of  cloth  or  any  other  suitable  material  at  hand  may 
be  used  as  a  substitute. 

Measuring  tape. — For  measuring  coal-bed  sections  a  20-foot  water- 
proof tape  graduated  to  one-fourth  inch  is  used.  A  steel  tape  grad- 
uated to  one-sixteenth  inch,  though  more  accurate,  is  less  convenient, 
as  the  figures  are  more  difficult  to  read  by  the  poor  light  available  in 
mines. 

Sample  can. — The  vessel  ordinarily  used  by  the  Bureau  of  Mines 
and  by  the  Geological  Survey  for  transporting  coal  samples  is  a  9  by 
3  inch  round  can  of  No.  27  galvanized  iron.  The  can  filled  with  coal 
should  not  weigh  more  than  4  pounds,  which  is  the  limit  of  weight  for 
ordinary  transmission  by  mail.  The  edges  of  the  can  are  crimped 
and  carefully  soldered  to  make  them  tight  and  strong;  the  screw  top 
(2  inches  in  diameter)  has  a  gasket  or  washer  of  rubber  or  other  flexi- 
ble material  to  exclude  the  air.  As  a  further  protection,  the  outside 
of  the  cap,  when  in  place  and  screwed  down  tightly,  is  wrapped  care- 
fully with  several  layers  of  adhesive  tape  so  that  the  first  layer  of 
this  tape  completely  covers  the  joint  between  the  lower  edge  of  the 
cap  and  the  neck  of  the  can.  It  is  not  advisable  to  use  solder, 
paraffin,  or  sealing  wax  of  any  kind.  Before  being  filled  each  can 
should  be  carefully  inspected  as  to  tightness  and  freedom  from  rust. 

Adhesive  tape. — For  sealing  the  connection  of  the  cap  and  sample 
can,  electrician's  adhesive  tape  of  the  best  quality  is  used. 
54333°— 18 2 


10  THE    SAMPLING    OF    COAL   IN    THE    MINE. 

Pick  and  shovel. — Nothing  is  better  than  a  miner's  pick  for  cutting 
samples.  A  miner's  shovel  should  be  taken  along  for  cleaning  up 
the  floor,  etc.  Pick  and  shovel  are  not  regularly  included  in  the  kit, 
as  they  can  be  had  at  any  working  mine. 

The  field  men  of  the  Geological  Survey,  because  they  often  work 
long  distances  from  a  base  of  supplies  and  travel  by  horseback,  usually 
carry  a  simpler  outfit  than  that  described  above,  consisting  of  a 
waterproof  blanket,  a  measuring  tape,  adhesive  tape,  a  screen,  a 
geologist's  pick,  an  improvised  shovel,  and  the  necessary  number 
of  sample  cans.  Instead  of  using  a  portable  mortar  and  pestle,  a 
man  thus  equipped  must  pulverize  the  coal  with  his  pick,  on  a  board 
or  other  hard  surface,  and  instead  of  a  scoop  he  must  use  a  trowel 
or  shingle.  He  does  not  weigh  the  coal;  and  instead  of  using  a 
brush  or  broom,  he  removes  loose  coal,  etc.,  from  the  face  and  roof, 
and  cleans  the  quarterings  off  the  sampling  blanket  with  a  piece  of 
cloth  or  any  other  suitable  means.  He  will  ordinarily  use  a  miner's 
pick,  if  found  in  the  mine,  instead  of  his  geologist's  pick  for  cut'ting 
down  the  coal. 

PRELIMINARY  DETAILS. 
SELECTING   PLACES    FOR    SAMPLING. 

A  map  of  the  mine  should  be  obtained  from  the  company's  office 
for  use  in  studying  the  layout  of  the  mine  with  a  view  of  selecting 
the  points  at  which  each  sample  is  to  be  collected.  These  points 
should  be  so  selected  that  the  samples  will  represent  the  character 
of  the  coal  available  in  the  mine  as  a  whole,  for  future  as  well  as 
for  present  shipment.  Exceptional  features,  such  as  "faults,"  etc., 
should  be  avoided  unless  special  studies  of  the  coal  at  such  places 
are  thought  desirable.  Where  possible  wet  places  should  be  avoided, 
as  samples  from  such  places  may  not  represent  the  coal  as  shipped. 
If  wet  coal  must  be  collected,  the  surplus  moisture  should  be  drained 
off  the  sampling  cloth  before  mixing  the  sample  and  the  fact  should 
be  stated  on  the  card  sent  to  the  chemical  laboratory. 

The  collector  must  necessarily  rely  on  the  mine  officials  for  infor- 
mation regarding  the  extent  and  direction  of  the  present  and  future 
developments  of  the  mine  and  the  situation  in  the  mine*  of  excep- 
tional features,  such  as  "faults,"  etc.,  for  ordinarily  time  does  not 
permit  him  to  make  an  extensive  survey  and  a  detailed  study  of  the 
mine  so  as  to  familiarize  himself  well  enough  with  all  conditions,  to 
enable  him  to  select  the  most  advantageous  points  for  sampling. 
The  points  selected,  however,  should  be  subject  to  change  as  the 
collector's  work  in  the  mines  progresses  if  he  finds  that  the  sections 
of  the  bed  at  the  points  selected  do  not  represent  the  bed  or  that 
operations  in  certain  parts  of  the  mine  are  liable  to  be  suspended  or 
permanently  abandoned. 


METHOD   OF   SAMPLING.  11 

NUMBER    OF    SAMPLES    TO    BE    COLLECTED. 

More  samples  should  be  collected  from  mines  in  which  the  quality 
of  the  coal  varies  greatly  than  from  mines  in  which  the  variation  is 
small.  Where  only  a  part  of  a  bed  is  being  mined,  and  the  remainder 
(1  foot  or  more  in  thickness)  is  being  left  underground,  separate 
samples  should  be  collected  at  each  sampling  place  of  both  the 
worked  and  the  unworked  parts  or  benches  of  the  bed.  In  sampling 
coal  beds  exposed  in  ordinary  prospect  openings,  where  the  coal  is 
usually  more  or  less  weathered,  one  sample  from  each  opening  is 
considered  enough  unless  the  openings  are  far  apart;  in  that  event, 
occasional  second  or  check  samples  are  highly  desirable.  From 
any  mine  that  is  shipping  coal  not  less  than  three  samples  should  be 
taken  and  the  number  to  be  taken  should  increase  with  increase  in 
the  daily  output  of  the  mine — not  less  than  three  samples  for  out- 
puts up  to  a  daily  average  of  300  tons,  four  samples  for  average 
outputs  of  300  to  500  tons,  five  samples  for  outputs  of  500  to  1,000 
tons,  six  samples  for  an  output  of  1,000  to  1,500,  and  an  additional 
sample  for  every  500  tons  daily  output  over  1,500  tons. 

METHOD  OF  SAMPLING. 
CLEANING    OFF   THE    FACE    OF   THE    COAL. 

At  each  selected  point,  before  a  sample  is  cut,  the  face  of  the  bed 
should  be  cleared  of  burned  powder,  dirt,  or  loose  coal  from  roof  to 
floor  for  a  width  of  about  5  feet.  This  is  done  to  prevent  any  loose 
fragments  or  foreign  matter  from  falling  off  the  face  of  the  coal  onto 
the  sampling  cloth.  Insecure  pieces  of  the  roof  should  also  be  taken 
down  in  advance  for  the  same  reason.  In  the  middle  of  this  cleared 
area  on  the  face,  the  coal  should  be  cut  away  with  the  pick  from  the 
roof  to  the  floor  for  a  width  of  1  foot  and  a  depth  of  at  least  1  inch 
or  to  a  greater  depth  as  may  be  required  with  a  view  to  removing 
any  discolored,  altered,  or  otherwise  inferior  coal  that  might  be 
near  the  surface,  and  also  to  square  up  this  portion  of  the  face  in 
preparation  for  the  sampling  cut. 

WHAT    TO    INCLUDE    IN   THE    SAMPLE. 

There  should  go  into  the  sample  as  it  is  cut  from  the  face  all  the 
material  that  ordinarily  goes  into  the  daily  shipments  of  coal.  There 
should  be  omitted  from  the  sample  only  such  material  as  is  ordinarily 
discarded  by  the  miner.  Usually  partings  more  than  three-eighths 
of  an  inch  thick  and  lenses  or  concretions  of  " sulphur"  or  other 
impurities  more  than  2  inches  in  maximum  diameter  and  one-half 
of  an  inch  thick  are  excluded,  if  in  the  judgment  of  the  sampler  they 
are  being  excluded  by  the  miner  from  the  coal  as  loaded  out  of  the 
mine  or  as  shipped.  If  such  impurities,  or  other  impurities,  are  not 


12  THE    SAMPLING   OF    COAL   IN    THE    MINE. 

generally  excluded  by  the  miner,  they  should  be  included  in  the 
sample.  If  pillars  are  being  " pulled/'  careful  note  should  be  made 
not  only  of  partings  but  of  materials  from  the  roof  that  are  not 
rejected  by  the  miner.  Where  the  impurity  to  be  rejected,  like  bone 
or  slaty  coal,  does  not  show  conspicuously,  it  is  advisable  to  outline 
the  impurity  with  chalk  in  advance  so  as  to  prevent  its  being  over- 
looked when  the  sample  is  cut. 

Imitating  the  miner  in  excluding  impurities  is  the  best  method, 
but  this  requires  care  and  judgment,  especially  where  the  partings 
are  soft  and  friable.  No  two  miners  can  be  relied  on  to  discard  the 
same  partings  to  the  same  extent,  even  at  mines  where  the  most  rigid 
regulations  for  cleaning  the  coal  are  in  force.  As  it  is  desired  to 
obtain  samples  that  represent  as  nearly  as  possible  the  coal  that  is 
produced  commercially  from  the  mine  under  examination,  the 
method  given  in  the  above  paragraph  should  be  followed  as  closely 
and  as  uniformly  as  possible.  The  carrying  out  of  this  method 
demands  the  exercise  of  judgment  and  experience  on  the  part  of  the 
sampler,  and  he  must  familiarize  himself  with  the  impurities  in  the 
coal  bed  and  their  relation  to  the  coal  which  is  shipped. 

COLLECTING  AND  PREPARING  THE  SAMPLE. 

The  collector  should  smooth  and  clean  the  floor  and  spread  the 
sampling  cloth  on  it  close  to  the  face  of  the  coal.  Then  he  should 
make  a  perpendicular  cut  2  inches  deep  and  6  inches  wide  (or  3 
inches  deep  and  4  inches  wide  in  the  softer  coals)  from  the  roof  to 
the  floor  down  the  middle  of  the  foot-wide  cut  previously  made  in 
the  coal  face.  He  should  be  careful  to  make  this  cut  uniform  in 
width  and  depth  and  should  chip  off  enough  coal  to  make  a  sample 
weighing  at  least  6  pounds  for  each  foot  of  the  thickness  of  the  bed; 
so  that  the  sample  collected  on  the  cloth  from  a  6-foot  bed  will 
weigh  not  less  than  36  pounds.  Inexperienced  collectors  should 
weigh  their  samples  (by  spring  balance  or  otherwise)  as  a  check  on 
the  accuracy  of  their  work. 

As  soon  as  the  cutting  of  the  sample  has  been  completed,  if  the  full 
outfit  previously  described  is  available,  the  finer  portions  of  the 
sample  should  be  put  through  the  J-inch  or  f-inch  screen  and  the 
lumps  should  be  broken  in  the  mortar  until  all  the  coal  passes  through 
the  screen.  The  sample  should  then  be  thoroughly  mixed  by  two  men 
grasping  the  opposite  corners  of  the  sampling  cloth  and  rolling  it 
diagonally  by  raising  one  .corner  at  a  time,  and  after  being  thoroughly 
mixed  should  be  formed  into  a  conical  pile  by  gathering  together 
the  four  corners  of  the  cloth.  Then  the  cloth  should  be  laid  on  the 
floor  and  the  top  of  the  pile  flattened  with  a  clean  dry  shovel,  trowel, 
or  board.  The  sample  is  then  quartered  and  two  opposite  quarters 
are  discarded  and  brushed  off.  The  remainder  is  mixed  as  before, 


METHOD   OF   SAMPLING.  13 

and  if  the  sample  is  still  too  bulky  for  convenient  handling  it  is 
again  quartered  down.  The  material  finally  remaining  is  spread 
into  a  circular  mass  about  2  inches  deep  on  the  cloth,  and  the  sam- 
pling- scoop  is  used  to  fill  the  sample  can  compactly  with  portions 
from  opposite  quarters.  The  entire  operation  described  above,  from 
the  cutting  of  the  sample  to  the  sealing  of  the  can,  should  be  done 
in  the  mine  so  as  not  to  expose  the  coal  to  the  outside  atmosphere. 

THE    CAN    SHOULD   BE    COMPLETELY   FILLED. 

It  is  important  that  the  coal  be  well  packed  in  the  can,  so  as  to 
occupy  as  much  of  the  space  as  possible,  for  in  that  way  the  air 
is  more  nearly  excluded.  This  is  best  accomplished  by  shaking  or 
jarring  the  can  repeatedly  and  vigorously  while  filling  it. 

LABELING. 

Each  sample  can  when  sent  out  should  have  a  number  printed  on 
it.  This  number  is  to  be  used  by  the  coUector  as  the  field  number 
for  the  sample  placed  in  that  can  for  analysis,  and  is  to  be  recorded 
in  his  notebook  and  on  his  cards.  Before  the  can  is  sealed,  a  folded 
label  should  be  placed  in  it  on  the  top  of  the  coal.  This  label  should 
bear  the  can  number,  the  name  and  location  of  the  mine,  the  name 
of  the  collector,  and  the  date.  Each  can  should  be  wrapped  with 
several  thicknesses  of  heavy  manila  paper  which  should  be  care- 
fully and  securely  tied.  Then  the  •  addressed  franked  wrapper 
should  be  pasted  on  or  tied  around  the  wrapped  can,  the  collector 
filling  in  the  blank  spaces  on  the  addressed  wrapper  with  information 
showing  the  name  of  the  collector  and  date  of  collection. 

SEALING   THE    CAN. 

As  soon  as  the  can  has  been  filled  and  the  label  (described  above) 
placed  inside,  the  cap  should  be  screwed  on  so  that  the  top  of  the 
screw  fits  tightly  into  the  rubber  or  other  flexible  material  in  the  cap  ; 
adhesive  tape  should  then  be  carefully  wrapped  around  the  lower 
outer  edge  of  the  cap  in  such  a  manner  as  to  cover  the  joint  and 
increase  the  thoroughness  of  the  sealing. 

NOTES. 

To  facilitate  the  gathering  and  recording  of  data  concerning  the 
samples  of  coal  and  the  mines  from  which  they  are  taken,  blank 
forms  have  been  prepared  for  the  use  of  collectors.  These  forms  can 
be  had  upon  application  to  either  the  Director  of  the  Bureau  of  Mines 
or  the  Director  of  the  Geological  Survey.  The  forms,0  which  are  of 
convenient  size  for  the  pocket,  indicate  what  information  is  desired 

a  Copies  of  the  forms  are  appended  to  this  circular. 


14  THE   SAMPLING   OF   COAL  IN   THE   MINE. 

concerning  the  nature  and  operations  of  the  mine,  the  number,  depth, 
and  character  of  the  beds  of  coal,  the  specific  location  from  which 
each  sample  was  taken,  and  the  exact  character  of  the  bed  at  the 
point  of  sampling,  and  make  specific  mention  of  bands  of  " sulphur" 
(pyrite,  etc.),  shale,  or  other  objectionable  material  that  should  be 
excluded  in  shipment. 

The  record  of  the  coal-sample  section  should  be  made  in  the  mine 
from  actual  measurements,  immediately  after  the  collection  of  the 
sample  and  the  sealing  of  the  sample  can. 

PROMPT   FORWARDING   AND    ANALYSIS    OF    SAMPLES. 

The  cans  containing  the  samples  should  be  delivered  by  the  col- 
lector in  person  to  the  nearest  post  office  for  forwarding  by  the  first 
mail  to  the  laboratory. 

It  is  expected  that  each  sample  on  its  receipt  at  the  laboratory 
will  be  placed  in  a  dark,  cool  place,  and  that  the  analysis  will  be 
completed  within  two  weeks. 

SENDING    NOTIFICATION    CARDS. 

The  cards,  supplied  in  advance  to  each  collector,  are  in  two  forms, 
A  and  B.  After  entering  certain  data  called  for  in  the  forms  the  col- 
lector forwards,  in  sealed  envelope,  one  card  A  for  the  mine  and  a 
card  B  for  each  sample,  to  the  Bureau  of  Mines  chemical  laboratory. 
As  soon  as  these  cards  and  the  corresponding  sample  are  received  at 
the  laboratory  a  statement  of  the  receipt  of  sample  is  then  sent  to 
the  chief  of  the  field  party,  in  order  to  give  notice  of  the  arrival  of  the 
sample.  Copies  of  these  cards  are  shown  on  pages  15  and  16. 

Special  attention  should  be  given  to  filling  out  and  promptly  for- 
warding these  cards.  Failure  to  fill  out  a  card  properly  or  to  for- 
ward it  promptly  may  cause  indefinite  delay  in  making  the  analysis 
of  a  sample. 


METHOD    OF    SAMPLING. 


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THE   SAMPLING   OF  COAL  IN   THE   MINE. 


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BLANK  FORMS  FOR  COLLECTORS.  17 

BLANK  FORMS  FOB  COLLECTORS. 

Copies  of  some  of  the  blank  forms  carried  by  the  engineers  of  the 
Bureau  of  Mines  for  recording  the  information  desired  regarding  a 
sample  of  coal  and  the  mine  from  which  it  is  taken  are  given  here- 
with. These  forms  are  printed  on  separate  sheets  that  are  perforated, 
and  are  intended  for  use  with  a  loose-leaf  binder.  They  make  a  note- 
book measuring  about  4J  by  7J  inches.  (See  folio  wing  pages,  forms 
B,  C,  D,  and  E  being  omitted  as  not  relating  to  character  of  coal.) 

DEPARTMENT  OF  THE  INTERIOR. 
BUREAU  OF  MINES. 


A. — Physical  features  of  the  mine. 

Name  of  collector 

Mine Date 

State County 

Township S T It 

Mine  location  (distance  and  direction  from  nearest  railway  station) 

Mine  railway  connections 

Operator  of  mine 

Address  of  operator 

Address  of  mine 

Superintendent ' 

Pit  boss 

Selling  agent 

Address 

Trade  name  of  coal 

Coal-bed  name Geologic  formation 

Kind  of  coal 

Average  thickness  of  coal  bed feet inches. 

Dip  of  bed °    Direction  of  dip 

Has  coal  "faces' '? Direction  of 

Faults ;  frequent? 

Rolls  or  horse  backs ;  frequent? 

Does  mine  make  methane? from  coal,  roof,  or  floor 

Quantity  evolved maximum  in  return per  cent. 

Entrance  to  mine :  Drift,  cross-drift,  slope,  shaft 

Elevation  of  entrance  above  sea,  barometric  reading Actual feet. 

Vertical  depth  to  bed  (below  entrance) feet. 

System  of  mining 

Is  mine  laid  out  with  reference  to  "butts' '  and  "faces' '? 

Entry  width,  main feet;  side  entry feet;  stub feet. 

Pillar  width,  main feet;  side  entry feet;  stub feet. 

Room  pillar  width feet;  barrier  pillar  width feet. 

Room  width feet;  room  length feet. 

Room  pillars  pulled? Entry  pillars  pulled? 

Proportion  of  coal  taken  in  advance  work 

Per  cent  recovery  excluding  roof  coal per  cent  including per  cent. 


18  THE    SAMPLING    OF   COAL   IN    THE    MINE. 

F. — Mining  conditions. 

Range  in  thickness  of  coal  as  mined :  From feet inches. 

to feet inches.    Average feet inches. 

Variability  of  partings  or  other  impurity  in  character  and  thickness? 

Roof  (a)  "Draw  slate"  (coming  down  with  coal) thickness. 

(6)  Shale,  quality,  color,  etc 

(c)  Roof  coal Quality Thickness 

(d)  Sandstone  or  limestone 

Is  immediate  roof  smooth  or  does  coal  stick? 

Does  immediate  roof  fall  in  rooms? 1 

Is  there  a  cap  rock  or  main  roof  above? 

Height  of  cap  rock,  etc. ,  above  coal feet. 

Do  particles  of  roof  get  mixed  with  coal  in  loading? 

Vertical  height  to  nearest  workable  coal  above feet. 

Vertical  depth  to  nearest  workable  coal  below feet. 

Floor  or  underclay: 

Kind 

Softness 

Smooth  or  rough 

Do  particles  get  mixed  with  coal? 

Is  coal  undercut  in  clay  floor  orin  coal? 

Undercut  by  hand  or  machine? 

Are  machine  cuttings  loaded  with  coal? 

FUTURE    OUTPUT  AND   PRODUCTION. 

Approximately  what  unmined  area  is  to  be  taken  out  from  present  opening? acres. 

What  is  probable  lifetime  of  mine? years. 

Is  the  tonnage  to  be  derived  from  advance  work  or  pillars 

In  what  proportions? 

Present  average  daily  output  of  mine tons  (2,000  pounds). 

Maximum  day's  run 

To  what  extent  is  daily  output  to  be  increased  or  diminished  in  future? 


G. — Preparation  for  market. 


Proportion  of  output  shipped  as  "run  of  mine" 

What  percentage  of  coal  going  to  screens  passes  through?. 


Type  of  lump  screens,  bar,  shaking,  etc.: 

Size  of  opening 

(a)  Bar,  length feet. 

Spaces,  width inches. 

(6)  Shaking  screen,  area feet  by feet. 

Diameter  of  holes inch. 

Type  of  small-coal  screens,  if  any: 

(a)  Bars,  length 

Space,  width inches. 

(6)  Shaking  screens,  area feet  by feet. 

Diameter  of  holes inch. 

(c)  Revolving  screens,  length feet. 

Diameter  of  holes inch. 

Diameter  of  mesh inch. 


BLANK  FORMS  FOR  COLLECTORS. 


19 


IB  coal  picked  on  belt  or  on  car? 

Numbers  of  pickers  (or  trimmers  who  pick) 

Are  screenings  washed? Maximum  size  washed inch. 

Sizes  produced  by  washing » 

Type  of  washery 

Average  daily  tonnage tons  (2,000  pounds). 

Are  screenings  coked? Are  they  crushed? 

Average  daily  tonnage  coal  coked 

What  storage-bin  capacity? tons. 

Appearance  of  lump  coal  on  cars. 

Lumps,  large  or  small? 

Appearance  of  screenings  on  cars 

Loading  tracks,  number  of 

Track  capacity  for  empty  railway  cars 

Track  capacity  for  loaded  railway  cars 

REMARKS: 

H. — Coal  sample  section. 

Mine Date, ,  191. . . 

State - Can  No 

County Township 

Name  of  bed  of  coal 

Location  of  mine 

Total  (vertical)  depth  from  surface  at  point  of  sampling feet. 

[In  describing  the  beds  and  character  of  the  members  note  any  member  that  is  rejected  by  the  miner. 
Note  all  clay  and  "sulphur"  partings,  whatever  their  thickness.  Exclude  from  sample  all  clay  and 
"sulphur"  partings  f  inch  thick  or  over  (and  even  those  of  less  thickness)  if  they  are  rejected  at  mine 
or  tipple.] 

Section  of  bed  at  point  sampled. 


Description. 


Roof  (main) 

Roof  (immediate) . 


Feet. 


No. 


1 
2 
3 
4 
5 
6 
7 
8 
9 

10 
11 
12 
13 
14 


Total 


Floor. 


Inches. 


20  THE    SAMPLING    OF    COAL    IN    THE    MINE. 

Is  coal  sample  wet  or  dry? 

Time  exposed hours minutes. 

Weight gross net. 

What  are  the  impurities  and  how  do  they  occur? 

What  impurities  are  shipped  with  the  coal? 

What  impurities  are  excluded  from  the  sample? 

Collector. . 


PUBLICATIONS  ON  SAMPLING  AND  ANALYSIS  OF  COAL.  21 

PUBLICATIONS  ON  THE  SAMPLING  AND  ANALYSIS  OF  COAL. 

A  limited  supply  of  the  following  publications  of  the  Bureau  of 
Mines  has  been  printed  and  is  available  for  free  distribution  until 
the  edition  is  exhausted.  Requests  for  all  publications  can  not  be 
granted,  and  to  insure  equitable  distribution  applicants  are  requested 
to  limit  their  selection  to  publications  that  may  be  of  especial  inter- 
est to  them.  Requests  for  publications  should  be  addressed  to  the 
Director,  Bureau  of  Mines. 

The  Bureau  of  Mines  issues  a  list  showing  all  its  publications 
available  for  free  distribution  as  well  as  those  obtainable  only  from 
the  Superintendent  of  Documents,  Government  Printing  Office,  on 
payment  of  the  price  of  printing.  Interested  persons  should  apply 
to  the  Director,  Bureau  of  Mines,  for  a  copy  of  the  latest  list. 

PUBLICATIONS   AVAILABLE    FOR   FREE   DISTRIBUTION. 

BULLETIN  28.  Experimental  work  conducted  in  the  chemical  laboratory  of  the 
United  States  fuel-testing  plant  at  St.  Louis,  Mo.,  January  1,  1905,  to  July  31,  1906, 
byN.  W.  Lord.  51pp. 

BULLETIN  85.  Analysis  of  mine  and  car  samples  of  coal  collected  in  the  fiscal  yeara 
1911  to  1913,  by  A.  C.  Fieldner,  H.  I.  Smith,  A.  H.  Fay,  and  Samuel  Sanford.  1914. 
444  pp.,  2  figs. 

BULLETIN  119.  Analyses  of  coals  purchased  by  the  Government  during  the  fiscal 
years  1908-1915,  by  G.  S.  Pope.  1916.  118  pp. 

BULLETIN  123.  Analyses  of  mine  and  car  samples  of  coal  collected  in  the  fiscal 
year  1913  to  1916,  by  A.  C.  Fieldner,  H.  I.  Smith,  J.  W.  Paul,  and  S.  Sanford,  1918. 
478  pp.,  2  figs. 

TECHNICAL  PAPER  8.  Methods  of  analyzing  coal  and  coke,  by  F.  M.  Stanton  and 
A.  C.  Fieldner,  1913.  42  pp.,  12  figs. 

TECHNICAL  PAPER  64.  The  determination  of  nitrogen  in  coal,  a  comparison  of 
various  modifications  of  the  Kjeldahl  method  with  the  Dumas  method,  by  A.  C. 
Fieldner  and  C.  A.  Taylor.  1915.  25  pp.,  5  figs. 

TECHNICAL  PAPER  76.  Notes  on  the  sampling  and  analysis  of  coal,  by  A.  C.  Field- 
ner. 1914.  59  pp.,  6  figs. 

TECHNICAL  PAPER  133.  Directions  for  sampling  coal  for  shipment  or  delivery,  by 
G.  S.  Pope.  1917.  15  pp.,  1  pi. 

TECHNICAL  PAPER  148.  The  determination  of  moisture  in  coke,  by  A.  C.  Fieldner 
and  W.  A.  Selvig.  1917.  13  pp. 

TECHNICAL  PAPER  172.  Effects  of  moisture  on  the  spontaneous  heating  of  stored 
coal,  by  S.  H.  Katz  and  H.  C.  Porter.  1917.  25  pp.,  1  pi.,  8  figs. 

PUBLICATIONS   THAT   MAY   BE   OBTAINED   ONLY   THROUGH    THE   SUPER- 
INTENDENT  OF   DOCUMENTS. 

BULLETIN  11.  The  purchase  of  coal  by  the  Government  under  specifications,  with 
analyses  of  coal  delivered  for  the  fiscal  year  1908-9,  by  G.  S.  Pope,  80  pp.  10  cents. 

BULLETIN  22.  Analyses  of  coals  in  the  United  States,  with  descriptions  of  mine  and 
field  samples  collected  between  July  1,  1904,  and  June  30,  1910,  by  N.  W.  Lord, 
with  chapters  by  J.  A.  Holmes,  F.  M.  Stanton,  A.  C.  Fieldner,  and  Samuel  Sanford. 
1912.  Part  I,  Analyses,  pp.  1-321;  Part  II,  Descriptions  of  samples,  pp.  321-1129. 
85  cents. 


22  THE   SAMPLING   OF   COAL   IX    THE    MIXE. 


IN  41.  Government  coal  purchases  under  specifications,  with  analyses  for 
the  fiscal  year  1909-10,  by  G.  S.  Pope,  with  a  chapter  on  the  fuel-inspection  laboratory 
of  the  Bureau  of  Mines,  by  J.  D.  Davis.  1912.  97  pp.,  3  pis.,  9  figs.  15  cents. 

BULLETIN  63.  Sampling  coal  deliveries  and  types  of  Government  specifications 
for  the  purchase  of  coal,  by  G.  S.  Pope.  1913.  68  pp.,  4  pla.,  3  figs.  10  cents. 

BULLETIN  116.  Methods  of  sampling  delivered  coal,  and  specifications  for  the 
purchase  of  coal  for  the  Government,  by  G.  S.  Pope.  1916.  64  pp.,  5  pis.,  2  figs. 
15  cente. 


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